Posture chair



mentor:

Gttornug' March 26, 1940- R. A. CRAMER ET AL POSTURE CHAIR OriginalFiled Nov. 22, 1937 Z W W s k r m Patented Mar. 26, 1940 PATENT OFFICEPOSTUBE CHAIR Roy A. Cramer and Jesse F. Cramer, Kansas ty, Mo.

Application November 22, 1937, Serial No. 175,766 Renewed February 2,1940 6 Claims. (c1. 155-151) This invention relates to posture chairsand has for its general object to produce a back support of usual typein such chairs, such as shown in our Patent No. 2,054,557, issuedSeptember 15,

1936, but which, in addition, has its' back support pivoted so that theoccupant may lean back and secure a restful rocking position whendesired. This result is secured by maintaining substantial equilibriumat any point throughout 10 the range of rocking movement so that theoccupant need exert no force in either direction to maintain balance.

Another object of the invention is to produce a spring back which notonly progressively increases its resistance to increasing load of thebody weight as the chair back recedes from the vertical as in the usualarrangement having helical springs, but also one in which the initialresistance of the spring to movement from posture position is great toavoid accidental recession of the back from posture position, thisconstruction being claimed in our copending application Serial No.270,982, filed May 1, 1939. After the occupant forcibly pushes or tripsthe back beyond posture position, the tension arrangement is such thatfor its range of rocking movement, the parts are in substantialequilibrium up until the chair has almost reached its limit of rockingmovement, when the resistance to backward movement of the chair backincreases more rapidly than the shift in the center of gravity of thebody weight, thus avoiding the possibility that the occupant willunintentionally swing the chair back to its fixed stop with the abruptblow now common with the ordinary type of spring mounting. In otherwords, with the chair of the invention, it takes a decided effort by theoperator, greater than mere body weight, to start the chair back fromposture position, the chair back then has a range of movement in whichthespring may be adjusted to balance increased body weight, and finallybefore the fixed stop is reached, the tension of the spring is increasedmore than is necessary to balance body weight,

making it necessary for the occupant to exert an additional force beforethe back of the chair can be forced back its full course of travel.

Another object of the invention is to provide a pivoted or rocking backfor chairs, of such nature that the back may be adjusted toward and fromthe seat in a straight line by a sliding movement without rocking theback or changing the relation between horizontal planes passing throughthe seat and back, whereby the chair can be adjusted for tall or shortoccupants without changing the tension resisting rearward tilting of theback as more particularly claimed in our copending application SerialNo. 270,982, filed May 1, 1939.

A further object of the invention is to produce a resilient cushion orchainseat having a flexible covering member secured in position againstshifting under the flexing of the seat or cushion due to body movementswhen the chair is in use, as more particularly claimed in our copendaEng1 9arzplication Serial No. 302,198, filed October With the generalobjects named in view and others as will hereinafter appear, theinvention consists in certain novel and useful features of 1construction and organization of parts as hereinafter described andclaimed; and in order that it may be fully understood, reference is tobe had to the accompanying drawing; in which:

Figure 1 is a side elevation of a chair embodying the invention.

Figure 2 is an enlarged fragmental side elevation, partly in section toillustrate the ten-' siorling device for the pivoted chair back supporFigure 3 is an inverted plan view of the chair seat or cushion toillustrate the method of securing the flexible cover to the cushion.

Figure 4 is a plan view of the spider supporting construction, the seathaving been removed.

Figures 5 and 6 are respectively bottom plan and edge views of a cushionembodying certain features of the cushion shown in Figure 2.

In the said drawing, where like reference characters identifycorresponding parts in all of u the figures, the supporting pedestalstructure will not be described in detail since it is shown in ouraforesaid Patent No. 2,054,557, other than to point out that the upperends of the legs I where welded to the spindle supporting casing 2, 40are preferably enclosed in a housing member 3 which reinforces andbraces the legs and adds a more finished appearance to the chair.Pivotally mounted on the upper end of the spindle 4 is a spider 5 tosupport the seat. Although this spider may be as shown in our previouspat ent, we have found that it is desirable to have the spring pressedlocking pin 6 rearwardly of the spindle instead of forwardly thereof asshown 5 in our previous patent, since it makes it possible to secure thesame range of adjustment of the back toward and from the seat with ashorter horizontally adjustable supporting bar I slidingly mounted in achannelled portion Ia of the spider ,tally adjustable support instead ofbeing upstanding to form a back support or standard as in our previouspatent, terminates in a downwardly and forwardly curved portion 9, whichis preferably of spring or resilient nature. Secured to the end of thecurved portion 8, which preferably terminates substantially parallel to,but underlying the main body of the member I, is an upstanding squaretube III slidingly but non-rotatably receiving a squared stem IIequipped at its lower end with a journaled anti-friction roller member I2. When the parts are assembled as hereinafter described, the roller I2cannot fall from position, but the parts may be provided with a lockingpin to prevent disengagement if thought desirable. The upper end of therectangular tube I8 is closed by a plug Illa, the latter being threadedfor engagement with adjusting bolt I3 having a hand wheel I4. The boltI3 is unconnected with, but is adapted to press against, the end of thenon-rotatable stem I I, and it will be apparent that by adjusting thehand wheel, the bolt I3 will project the stem II carry-. ing the rollerI2 for tensioning purposes as will hereinafter appear.

Welded or otherwise secured to the bar mem ber I forwardly of itsresilient portion 9 is a fixed block member I5. Embracing the downwardlycurved spring end of the bar I, but spaced therefrom, is a yoke memberI6 which is provided with a pivot pin mounting I'I journaled in thefixed block I5. The closed end of the yoke fixedly carries an uprightstandard or back member I8, the latter at its upper end carrying avertically and tiltably adjustable back rest I9, such as shown in ourpatent aforesaid. The lower end of the back member I8 is bent forwardlyto form a cam surface or track I'Ba, it being understood in thisconnection that the cam or track member, although preferably ofresilient or spring nature, can be unyielding, the entire resiliencybeing in the member 9. In other words, either one of the members 9 orI9a may be resilient, or both may be resilient as shown, withoutchanging the operation of the chair. The cam member I9a is adapted to bein constant contact with the roller I2, and it will be apparent that byadjusting the hand wheel I4, the tension on members 9 and I9a, andconsequently the pressure on the back support to be overcome by the bodyweight of the occupant, may be set at the desired limit. Thus, byregulating the distance between the ends of members 8 and I9a, throughthe operation of the tensioning means (the hand wheel I4, bolt I3, androller I2), the force resisting rearward rocking or swinging of the backmember I8, may be adjusted. Stop means must be provided to limit theforward and rearward swinging of the back member. To limit forwardmovement, the front lower corner of the yoke I6 carries a cross pin 20,which, by contact with one side of the U-spring member 9, prevents theback member I8 from being thrown forwardly of a substantially verticalposition, as shown in Figures 1 and 2. To reinforce the yoke I8 its rearlower corner is strengthened by a cross pin 2| which also acts to limitrearward swinging movement of the back member I8, since as the yoke I6and the back member rigidly secured thereto, swing around the axis ofthe pivot bolt I1, the cross pin 28 moves away from the spring member 8while the cross pin 2| approaches the opposite side of said springmember; and when contact occurs between members 8 and 2| furtherswinging movement of the back member is prevented as there is noresiliency in the small length of the member 9 between the point ofcontact of cross pin 2| .and the pivotal point I1.

It has been found that by forming a depressed portion 22 in the frontend of the cam track Isa (see Figure 2), corresponding to posture orupright position of the back standard, considerable resistance isoffered to' recession of the chair back, this resistance, of course,being subject to manual adjustment by the hand wheel I4. After the chairback has passed rearwardly of posture position, it will be evident byconsideration of the dotted arc a-a, struck from the center of rotation,the axis of the pin I1, Figure 2, that the curvature of the cam trackI8w as it moves past the roller l2, will entirely control the degree oftension of the members at any predetermined angle of tilt of the backmember of the chair. In helical spring back chairs, the tension of thespring is practicallyalways in direct proportion to the extent ofswinging movement, but with our cam track arrangement it will beapparent that the curvature of the track can be such as to give anydesired rate of increase in tension.

As previously mentioned, the chair seat is preferably of sponge rubberor the like, and by preference, the chair bottom or base plate 23 isprovided with a multiplicity of openings 24 to permit of ready entranceand exit of air to the interstices in the cushion. To hold the cushionin proper position, it is usually glued, and in addition, it ispreferably to form the side margin of the base plate with an upturnedflange 25 which snugly embraces the edge of the cushion. The cushion isthen completely covered by a flexible fabric 28, the side edge of thecover underlying the base plate and being hemmed to receive a draw cord21 underlying the base plate. To hold the cover in proper position andunder tension, one end of the draw cord is secured to one of a series ofdownwardly extending ears 28 constituting limiting abutments for thedraw cord, said ears projecting from the base plate 23, and spacedinwardly from the margin of the seat. The other end of the draw cord isprovided with a resilient spring terminal 29 engaged with one of theears 28 to effect the return of the seat cover to proper position if itis pulled to one side or the other under the pressure of the seatoccupan In Figures 5 and 6, the cushion member is shown as comprising apad of resilient rubber 30. The rubber pad is covered by a fabriccovering 3| having its edge tubular to receive a flexible cord 32 bymeans of which the cover is stretched smoothly and underlies themarginaledge of the pad. To prevent the bottom edge of the seat cover from beingpulled from the position shown in Figure 5 at any side of the seat, aseries of tapes 38 are stitched to opposite edges of the cover. Straintending to pull one side of the cover is thereby transmitted to anopposing side or portion of the cover.

From the above description it will be apparent that we have produced achair and cushion embodying all the features of advantage set forth asdesirable, and while we have described and illustrated the preferredembodiment, it is to be understood that. we reserve the right to allchanges within the spirit of the invention and without the ambit of theprior art.

We claim:

1. In a chair, a seat support, a supporting member secured to the rearof the seat support and having a rearward and downwardly curvedresilient extension, a tensioning device on the end of the extension, aback member pivotally connected with the supporting member, said backmember having a lower cam-like resilient extension of graduallyincreasing curvature slidably engaging the end of the tensioning device,whereby the spring tension on the supporting member extension and on thecam-like extension is increased as the back member is swung rearwardly.

2. In a chair, a seat support, a supporting member secured to the rearof the seat support and having a rearward and downwardly curvedresilient extension, a tensioning device on the end oi! the extension, aback member pivotally connected with the supporting member, said backmember having a lower cam-like extension of gradually increasingcurvature slidably engaging the end of the tensioning device, wherebythe spring tension on the supporting member extension is increased asthe back member is swung rearwardly.

3. In a chair, a seat support, a supporting member secured to the rearof the seat support and having a downwardly curved extension, atensioning device on the end of the extension, a back member pivotallyconnected with the supporting member, said back member having a lowercam-like resilient extension of gradually increasing curvature slidablyengaging the end of the tensioning device, whereby the spring tension onthe cam-like extension is increased as the back member is swungrearwardly.

4. In a chair, a seat support, a seat carried by said seat support, aback supporting member carried by the seat support, a back memberpivotally connected to the back supporting member, said back supportingand back members each having an extension, one of said extensions beingresilient, and a tensioning device carried at one of its ends by one ofsaid extensions, said tensioning device having its opposite end abuttingagainst the other extension, said extensions being so shaped that theforce imposed by the resilient extension tends to pivot the back memberforwardiy toward the seat when the back member is tilted rearwardly.

5. In a chair, a seat support, a seat carried by said seat support, aback supporting member carried by said seat support, a back memberpivotally connected to said back supporting member and provided with anextension, a leaf spring projecting from the back supporting member, anda tensioning device carried by said leaf spring and abutting theextension, the shape of the extension being such that the distance fromthe pivotal point of the back member to the point of contact of thetensioning device on the extension gradually decreases on rearwardpivotal movement of the back member to increase the tension on said leafspring.

6. In a chair, a seat support, a seat carried by the seat support, aback supporting member carried by the seat support, said back supportingmember being mounted on the seat support for relative back and forthhorizontal adjustment with respect to the seat, a back member pivotallyconnected to the back supporting member, a back rest carried by the backmember, tensioned resilient means between the back member and backsupporting member resisting rearward pivotal movement of the back memberwhen force is imposed on the back rest, the tension imposed on saidresilient means being unaffected by the back and forth horizontaladjustment of the back supporting member with respect to the seat, andmanually operable mechanism for adjustably regulating the tensionimposed on said resilient means.

ROY A. CRAMER. JESSE F. CRAMER.

